Girder for timber bridges



Nov. 2, 1943. w. K. MERRIDITH 2,333,327

GIRDER FOR TIMBER BRIDGES Filed Nov. 23, 1942 2 Sheets-Sheet 1 3mm W. K.MERR/D/TH,

Nov. 2, 1943.. MERRIDWH 2,333,327

GIRDER FOR TIMBER BRIDGES Filed Nov. 23, 1942 v 2 Sheets-Sheet 2grwe/wfob PM K. MERR/D/TH,

1 S the lower log of the girder.

Patented Nov. 2, 1943 UNITED STATES 2,333,327 GIRDER FOR TIMBER BRIDGESWilliam K. Merridith, Sappho, Wash.

Application November 23, 1942, Serial No. 466,617

6 Claims.

This invention relates to girders adapted for use in many relations butmore particularly applicable in the construction of timber bridges.

Broadly stated, the invention resides in providing a girder consistingof two long logs, one disposed above the other, with the larger or buttend of one log disposed toward the smaller end of the other log,together with novel means hereinafter described, for securing these logstogether in such manner as to provide an exceedingly strong and rigidgirder. Further objects and advantages of the invention will be setforth in the detailed description which follows.

In the accompanying drawings:

Fig. 1 is a side elevation of a girder constructed in accordance withthe invention;

Fig. 2 is an end elevation looking from the right hand end of Fig. 1;

Fig. 3 is a plan view of the structure of Fig. 1;

Fig. 4 is a transverse sectional view upon line 44 of Fig. 1;

Fig. 5 is a fragmentary longitudinal sectional view through one of thekey blocks hereinafter described.

Like numerals designate corresponding parts in all of the figures of thedrawings.

In the drawings 5 designates the upper log and The invention, of course,is not restricted to logs of any particular size. However, in somesections of the country as, for example, in the Pacific Northwest it ispossible to secure very long and large logs for the manufacture ofgirder units embodying the features of this invention. In carrying outthe invention I have employed logs 112 feet 1 in length with a thicknessof 5 feet at the butt and 3 feet at the top or smaller end. By reversingthe logs, as shown, not only is the girder made of uniform strengththroughout its length but its upper and lower faces are caused to lie insubstantial parallelism with each other. Transverse members I, 8 and 9constituting cap stays, spacing stays and bottom stays respectively aredisposed at spaced intervals along the length of the girders and aretied together by vertical binding bolts ll) which lie outside of thelogs but pass through the stays, as is clearly illustrated in Fig. 4.Wire rope ties ll encircle the logs 5 and 6 and bind them together andagainst the spacing stays 8. At each end of the girder a wedge like endpost l2-l3 is shaped to engage a bevelled face Id of log 5 and the upperface i5 of log 6. Since the disposition of these faces is such as topresent, in effect, an outwardly flaring seat, it follows that when theend FATENT OFFICE posts are drawn forcibly inward they are caused toexert a wedging action between these surfaces. Since the stays 1 and 9,bolts l6 and wire wraps H prevent the logs from moving outwardly andaway from each other, it follows that when the end posts are thus drawninto keyed relation to said logs the resultant structure is made so veryrigid as to cause the girder to serve substantially as though it weremade in one piece. When so braced a girder of this character willsupport an exceedingly heavy load. One girder of this type, of which Ihave knowledge, is handling a, 200 ton locomotive and its loaded trainwith perfect safety. The means for drawing the end posts forcibly intothe keyed relation described consists of long bolts or threaded rods I!which pass through the lower log and through the end posts. Nutsthreaded upon said rods act against wear plates It. The

girder may be utilized to support any suitable.

type of roadway. As illustrating one of these uses I have shown lightstringers l9 supported upon the cap stays I, said stringers, in turn,carrying cross ties 28 for the support of track rails 2|.

It is to be understood that the invention is not limited to the preciseconstruction set forth but that it includes within its purview whateverchanges fairly come within either the terms or the spirit of theappended claims.

Having described my invention, what I claim 1s:

1. A girder comprising a pair of tapered, spaced logs reversed end forend with respect to each other and one being disposed over the othermeans disposed along the length of the girder for drawing said logstoward each other and resisting their separation, wedge like end postsengaging the ends of said logs, said end posts being so shaped as toexert a wedging action tendingto thrust said logs apart, and means forexerting a drawing action upon said end posts to draw them forciblyinward to exert such wedging action.

2. A girder comprising a pair of tapered, spaced logs reversed inposition with respect to each other so that the large end of one loglies opposite the small end of the other log and vice versa and one ofsaid logs being disposed over the other, a plurality of upper crossstays disposed at spaced intervals along the top of the top log, aplurality of lower cross stays disposed. beneath the lower log, bindingrods for drawing the upper and lower stays forcibly toward each other, awedge like post at the end of the girder,

one end of which engages a bevel end of one of the logs and the otherend of which engages a side face of the other of said logs and means fordrawing the end post forcibly toward said logs, to cause it to exert awedging action between said logs.

3. A structure as recited in claim 2 wherein the drawing means comprisesa threaded rod passing through the end post and through one only of saidlogs.

4. A structure as recited in claim 2 wherein said drawing meanscomprises a threaded rod passing through the end post and through thelowermost of said logs.

5. A structure of the character described cnmprising a pair of taperinglogs having their butt ends reversed with respect to each other, one ofsaid logs being disposed ahovetthe either transverse spacing staysbetween the said logs at spaced intervals therealong, transverse top andbottom stays aligned with the spacing stays, binding bolts passingvertically through said stays outside of said logs and acting to drawthe top and bottom stays into forcible engagement with said logs and todraw said logs into forcible engagement with the spacing stays, wirerope strands embracing the logs at spaced intervals along the length ofthe girder and wedge like end posts acting betweensaid logs adjacenttheir ends.

6. A structure as recited in claim 5 in combination with means fordrawing said end posts inwardiy, means comprising threaded rods passingthrough the posts and passing oblique- Iy through one only of said logs.

WILLIAM K. MERRIDITH.

